Image-enhanced cloud and fog masking target retrieval imaging method and device

Abstract

The present application relates to the technical field of image processing, and more particularly to a cloud and fog sheltered target inversion imaging method and device for image enhancement, wherein the method comprises: obtaining a reflected three-dimensional light field of a cloud and fog sheltered target; constructing an image enhancement filter function, and performing convolution operation on the reflected three-dimensional light field and the image enhancement filter function to obtain an enhanced filtered light field; performing frequency domain filtering on the enhanced filtered light field based on a cloud and fog transmission function; and based on the frequency domain filtered light field, performing target light field inversion imaging through a free space inversion method. The present application can improve the signal-to-noise ratio and contrast of cloud and fog sheltered target inversion imaging, and can meet the high resolution imaging requirement for cloud and fog sheltered targets.

Description

Technical Field

[0001] This invention relates to the field of image processing technology, and in particular to a method, apparatus, electronic device, and storage medium for image enhancement of cloud-obscured target inversion imaging. Background Technology

[0002] The scattering effect of clouds and fog severely limits the ability of optical detection and ranging systems to image through clouds and fog. The method of dividing the transmission of light field in space into different parts, accurately simulating the light transmission process of each part, and finally retrieving the target image has gradually become the mainstream method for imaging through clouds and fog.

[0003] Currently, when performing inversion imaging on targets obscured by clouds and fog, the inverted target image often suffers from low contrast with the background and poor overall image clarity due to cloud and fog scattering and noise. Summary of the Invention

[0004] Existing technologies for inverting and imaging targets obscured by clouds and fog often suffer from low contrast between the target image and the background, resulting in poor overall image clarity. This invention provides an image-enhanced method, apparatus, electronic device, and storage medium for inverting and imaging targets obscured by clouds and fog.

[0005] In a first aspect, the present invention provides an image-enhanced method for inverting and imaging targets obscured by clouds and fog, comprising:

[0006] Acquire the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range during which the pulse light is collected after being reflected by the target and penetrating the clouds and fog;

[0007] An image enhancement filtering function is constructed, and the reflected three-dimensional light field is convolved with the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is:

[0008]

[0009] Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time;

[0010] Based on the cloud and fog transfer function, frequency domain filtering is performed on the enhanced filtered light field;

[0011] Based on the frequency-domain filtered light field, the target light field is inverted and imaged using the free-space inversion method.

[0012] Optionally, acquiring the reflected three-dimensional light field of the target obscured by clouds and fog includes:

[0013] Illuminate targets obscured by clouds and fog with a monochromatic pulsed laser;

[0014] On the transmitting side, a single-photon detector is used to acquire the time-domain optical signal waveform of each two-dimensional spatial point by scanning. The time-domain optical signal waveform includes the peaks caused by target reflection, but does not include the peaks caused by cloud and fog reflection.

[0015] Based on the spatial positional relationship of the two-dimensional scanning points, the time-domain optical signal waveforms corresponding to each scanning point are combined to obtain the reflected three-dimensional light field.

[0016] Optionally, the expression for the cloud and fog transmission function is:

[0017]

[0018]

[0019] Where t represents the transmission time of the optical signal, and r = (r x ,r y ,r z ) represents the point in the cloud from which the light signal is emitted, r x r y and r z Let x, y, and z represent the coordinates of the exiting cloud point, respectively, where z is the direction of light diffusion in the cloud, r0 = (0,0,0) represents the incident point of the light signal in the cloud, c represents the speed of light in the cloud, and μ' s μ represents the reduced scattering coefficient of clouds and fog. a The value represents the absorption coefficient of clouds and fog, and D represents the diffusion coefficient. z +n Indicates the virtual point source location, z -n This indicates the location of the virtual negative point source, and n represents the number of positive and negative point source pairs.

[0020] z +n =(1-2n)r z -4nz e -z0

[0021] z -n =(1-2n)r z -(4n-2)z e +z0

[0022] n = 0, ±1, ±2, ...

[0023] z e z represents the extrapolated boundary distance, and z0 represents the average scattered optical path.

[0024] Optionally, the image enhancement filtering function includes:

[0025] Determine the frequency ω of the sine function based on the spatial interval Δr between points in two-dimensional space. c represents the speed of light in clouds and fog;

[0026] Based on the spatial interval Δr of the two-dimensional spatial points, determine the width a of the rectangular window function, where a is 10 to 15 times Δr;

[0027] The center position t0 of the rectangular window is determined based on the number of discrete sampling points of the image enhancement filtering function;

[0028] The image enhancement filtering function is obtained.

[0029] Optionally, the step of performing frequency domain filtering on the enhanced filtered light field based on the cloud and fog transfer function includes:

[0030] Based on the cloud and fog transfer function, the enhanced light field is frequency-domain filtered by blind deconvolution filtering, minimum mean square error filtering, geometric mean filtering, or least squares filtering.

[0031] Optionally, the free-space light field inversion method includes:

[0032] Frequency beam shifting method, optical cone transformation method, back projection method, or virtual wave phasor field method.

[0033] Secondly, the present invention provides an image enhancement device for inverting and imaging targets obscured by clouds and fog, comprising:

[0034] The acquisition module is used to acquire the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range in which the pulse light penetrates the clouds and fog after being reflected by the target and is collected;

[0035] The enhancement module is used to construct an image enhancement filtering function and convolve the reflected three-dimensional light field with the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is:

[0036]

[0037] Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time;

[0038] The filtering module is used to perform frequency domain filtering on the enhanced filtered light field based on the cloud and fog transfer function;

[0039] The inversion module is used to invert the target light field image based on the frequency domain filtered light field using the free space inversion method.

[0040] Thirdly, the present invention also provides an image-enhanced method for inverting and imaging targets obscured by clouds and fog, comprising:

[0041] Acquire the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range during which the pulse light is collected after being reflected by the target and penetrating the clouds and fog;

[0042] An image enhancement filtering function is constructed, and the reflected three-dimensional light field is convolved with the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is:

[0043]

[0044] Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time;

[0045] The characteristics of clouds and fog are determined, and a boundless cloud and fog transfer function is obtained. These characteristics include the reduced scattering coefficient of the clouds and fog, the speed of light within the clouds and fog, and the maximum thickness of the clouds and fog. The boundless cloud and fog transfer function φ... inf The expression for (t,r) is:

[0046]

[0047]

[0048] Where t represents the transmission time of the optical signal, and r = (r x ,r y ,r z ) represents the point in the cloud from which the light signal is emitted, r x r y and r z Let x, y, and z represent the coordinates of the exiting cloud point, respectively, where z is the direction of light diffusion in the cloud, r0 = (0,0,0) represents the incident point of the light signal in the cloud, c represents the speed of light in the cloud, and μ s ' represents the reduced scattering coefficient of clouds and fog, z effect This represents the equivalent propagation distance, where light travels through an infinitely large cloud. effect The diffusion behavior of light is similar to the propagation of light in clouds of finite size. z The diffusion behavior is equivalent to z effect Not exceeding the maximum thickness d of the cloud / fog;

[0049] The equivalent propagation distance z effect As a variable, the enhanced filtered light field is frequency-domain filtered based on the aforementioned unbounded cloud and fog transport function, and then the target light field is inverted using the free-space light field inversion method to determine the equivalent propagation distance z. effect The correspondence between the inverted target light field imaging results and the actual results;

[0050] Based on the equivalent propagation distance z effect The correspondence between the inverted target light field imaging results and the final imaging results is determined by parametric scanning or optimization solution.

[0051] Fourthly, embodiments of the present invention also provide an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the cloud-obscured target inversion imaging method described in any embodiment of this specification.

[0052] Fifthly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the cloud-obscured target inversion imaging method described in any embodiment of this specification.

[0053] The above-mentioned technical solution of the present invention has the following advantages: The embodiments of the present invention provide an image enhancement method, device, electronic device and storage medium for inverting and imaging targets obscured by clouds and fog. The present invention proposes a sine function with a rectangular window as an image enhancement filtering function. By convolving the reflected three-dimensional light field of the target obscured by clouds and fog with this function and then filtering and inverting, the target image is enhanced and the signal noise is suppressed, effectively improving the signal-to-noise ratio and contrast of the inverted imaging of targets obscured by clouds and fog, and meeting the requirements for high-resolution imaging of targets obscured by clouds and fog. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the steps of an image enhancement method for retrieving and imaging targets obscured by clouds and fog, provided in an embodiment of the present invention;

[0055] Figure 2 A schematic diagram of the time-domain distribution of the image enhancement filter function;

[0056] Figure 3(a) is an original image of the reflected three-dimensional light field of a target obscured by clouds;

[0057] Figure 3(b) is the image after convolving the light field with the image enhancement filter function corresponding to Figure 3(a);

[0058] Figure 3(c) is the scattered field image after frequency domain filtering of the light field corresponding to Figure 3(b);

[0059] Figure 3(d) is the target scattering field image obtained by inverting the light field corresponding to Figure 3(c);

[0060] Figure 4(a) is the inversion image of the cloud-covered target without the image enhancement filtering step;

[0061] Figure 4(b) is the inversion image of the cloud-covered target after the image enhancement filtering step;

[0062] Figure 5 This is a hardware architecture diagram of an electronic device provided in an embodiment of the present invention;

[0063] Figure 6 This is a structural diagram of a cloud-obscured target inversion imaging device provided in an embodiment of the present invention. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] The scenario of target inversion imaging obscured by clouds and fog can be considered as having a medium (i.e., clouds and fog) of a certain thickness between the detection plane and the target location. As mentioned earlier, when performing inversion imaging on targets obscured by clouds and fog, due to cloud and fog scattering and noise effects, the inverted target image often exhibits low contrast with the background, resulting in poor overall image clarity. In view of this, this invention provides a method for inverting and imaging targets obscured by clouds and fog that incorporates image enhancement filtering technology. This method aims to study the impact of optical field filtering technology on the inverted image of targets obscured by clouds and fog, effectively enhancing the target image and filtering out high- and low-frequency noise.

[0066] The specific implementation of the above concept is described below.

[0067] Please refer to Figure 1 This invention provides an image enhancement method for inverting and imaging targets obscured by clouds and fog, the method comprising the following steps:

[0068] Step 100: Obtain the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range during which the pulse light is collected after being reflected by the target and penetrating the clouds and fog.

[0069] Step 102: Construct an image enhancement filtering function, and convolve the reflected three-dimensional light field with the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is:

[0070]

[0071] Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time, representing the time dimension of the image enhancement filtering function; a schematic diagram of the time-domain distribution of an image enhancement filtering function is shown below. Figure 2As shown;

[0072] Step 104: Based on the cloud and fog transfer function, perform frequency domain filtering on the enhanced filtered light field;

[0073] Step 106: Based on the frequency-domain filtered light field, the target light field is inverted and imaged using the free-space inversion method.

[0074] The cloud-obscured target inversion imaging method provided in this invention convolves the three-dimensional light field reflected by the cloud-obscured target with a specific form of function (i.e., image enhancement filtering function), which is equivalent to filtering in the frequency domain. This can enhance or suppress specific frequency components in the signal, thereby improving the signal-to-noise ratio and contrast of the cloud-obscured target inversion imaging.

[0075] Figures 3(a) to 3(d) The images shown, in sequence, are the original image of the three-dimensional light field reflected from the target under cloud cover, the image after convolution with an image enhancement filter function, the image of the scattered field (also known as the light field) after frequency domain filtering, and the image of the target's scattered field obtained through inversion. These images are presented for ease of display. Figures 3(a) to 3(d) The maximum value of the corresponding 3D image in the z-axis direction (i.e., the time domain direction) is taken and displayed as a 2D image. Figure 4(a) is the inversion image of the cloud-obscured target without the image enhancement filtering step (i.e., without step 102), and Figure 4(b) is the inversion image of the cloud-obscured target after the image enhancement filtering step. Figures 3(a) to 4(b) As shown, the image enhancement method for cloud-covered target inversion imaging provided by the present invention can effectively invert target images, improve the signal-to-noise ratio and contrast of cloud-covered target inversion imaging, and meet the requirements for high-resolution imaging of cloud-covered targets.

[0076] Optionally, step 100, "obtaining the reflected three-dimensional light field of the target obscured by clouds and fog," further includes:

[0077] Laser emission: Illuminating the target obscured by clouds and fog with a monochromatic pulsed laser from the emitting side;

[0078] Two-dimensional spatial scanning: On the transmitting side, a single-photon detector is used to acquire the temporal optical signal waveform of each two-dimensional spatial point by scanning; the temporal optical signal waveform includes the peaks caused by target reflection, but does not include the peaks caused by cloud and fog reflection.

[0079] Waveform combination: Based on the spatial positional relationship of the scanning points in two-dimensional space, the time-domain optical signal waveforms corresponding to each scanning point are combined to obtain the reflected three-dimensional light field.

[0080] The above embodiments provide a method for obtaining the temporal waveform at each spatial scanning point by irradiating with a monochromatic pulsed laser and performing a two-dimensional spatial scan, thereby obtaining the reflected three-dimensional light field of a cloud-obscured target through actual measurement. In other embodiments, to verify the effectiveness of this cloud-obscured target inversion imaging method, the reflected three-dimensional light field can also be obtained by simulating the irradiation of the cloud-obscured target with monochromatic pulsed electromagnetic waves. Optionally, in some other embodiments, multiple detectors can be used to obtain the temporal optical signal waveform at two-dimensional spatial points, which has the advantages of saving scanning time and fast processing speed.

[0081] Furthermore, the image enhancement filtering function constructed in step 102 includes:

[0082] Determine the frequency ω of the sine function based on the spatial interval Δr between points in two-dimensional space. c represents the speed of light in clouds and fog;

[0083] Based on the spatial interval Δr of the two-dimensional spatial points, determine the width a of the rectangular window function, where a is 10 to 15 times Δr;

[0084] The center position t0 of the rectangular window is determined based on the number of discrete sampling points of the image enhancement filtering function;

[0085] The image enhancement filtering function is obtained.

[0086] The above embodiments provide a specific method for determining the parameters of an image enhancement filter function. This method enables the rapid construction of an image enhancement filter function. Generally, the total length of an image enhancement filter function is 2 to 4 wavelengths. The specific value of t0 can be determined based on the density of discrete sampling points, but regardless of the density, t0 will always be located at the center of the filter function. Repeated verification shows that after enhancement using the image enhancement filter function, specific frequency components in the signal can be effectively enhanced or suppressed, improving the target imaging results.

[0087] Optionally, the expression for the cloud and fog transmission function is:

[0088]

[0089]

[0090] Where t represents the transmission time of the optical signal, and r = (r x ,r y ,r z ) represents the point in the cloud from which the light signal is emitted, r x r y and r z Let x, y, and z represent the coordinates of the exiting cloud point, respectively, where z is the direction of light diffusion in the cloud, r0 = (0,0,0) represents the incident point of the light signal in the cloud, c represents the speed of light in the cloud, and μs ' represents the reduced scattering coefficient of clouds and fog, μ a The value represents the absorption coefficient of clouds and fog, and D represents the diffusion coefficient. To accurately simulate the collimated light pulse in the transmission function, a series of virtual point sources are needed to replace the collimated light source. +n Indicates the virtual point source location, z -n This indicates the location of the virtual negative point source, and n represents the number of positive and negative point source pairs.

[0091] z +n =(1-2n)r z -4nz e -z0

[0092] z -n =(1-2n)r z -(4n-2)z e +z0

[0093] n = 0, ±1, ±2, ...

[0094] z e z represents the extrapolated boundary distance, and z0 represents the average scattered optical path.

[0095] Optionally, the reduced scattering coefficient μ of the clouds and fog s It can be determined in the following way:

[0096] Obtain the reflected light field from clouds and fog;

[0097] The expression for the light field reflected by clouds and fog is:

[0098]

[0099] in, For the average scattering free path, μ is the diffusion coefficient. a μ is the absorption coefficient, typically... a Much smaller than μ' s Generally, this can be disregarded;

[0100] Taking the derivative with respect to R(t,r) yields:

[0101]

[0102] Let t be the time corresponding to when R(t,r) reaches its extreme value. max ;

[0103]

[0104] By differentiating the acquired reflected light field from the clouds and fog, and determining the corresponding parameters, the reduced scattering coefficient μ' of the clouds and fog can be determined. s The specific value.

[0105] Optionally, step 104 includes:

[0106] Based on the cloud and fog transfer function, the enhanced light field is frequency-domain filtered by blind deconvolution filtering, minimum mean square error filtering, geometric mean filtering, or least squares filtering.

[0107] Depending on the selected overall optical field transmission model, different frequency domain filtering methods can be employed. The overall optical field transmission model represents the overall transmission model of light in different parts of space. For example, when the overall optical field transmission model does not consider noise introduced by the environment, blind deconvolution filtering can be selected for frequency domain filtering. The above embodiments provide some commonly used frequency domain filtering techniques; in other embodiments, other frequency domain filtering methods can also be used to perform frequency domain filtering on the enhanced filtered optical field.

[0108] Further, step 104 includes:

[0109] Based on the cloud and fog transmission function, the enhanced filtered light field is frequency domain filtered by minimum mean square error filtering.

[0110] The expression for the scattered field after frequency domain filtering is:

[0111]

[0112] Where t represents the transmission time of the optical signal, and r = (r x ,r y ,r z () indicates the point in the cloud from which the light signal is emitted. For φ inf (t,r)*φ inf The frequency domain discretization representation of (t,r), where * denotes a three-dimensional convolution operation. for The conjugate matrix, F denotes the Fourier transform operation, F -1 This represents the inverse Fourier transform operation, where τ is the reflected three-dimensional light field after enhancement filtering. The discretized representation of α represents the noise term parameter related to the signal power spectrum and the noise power spectrum.

[0113] The above embodiments perform frequency domain filtering on the enhanced reflected three-dimensional light field through minimum mean square error filtering. Minimum mean square error filtering is applicable to scenarios in the overall light field transmission model that consider noise terms introduced by the environment. Usually, when the specific signal power spectrum and noise power spectrum are unknown, α can be set to a certain fixed value to achieve frequency domain filtering of the reflected three-dimensional light field.

[0114] Optionally, in step 106, the free-space light field inversion method includes:

[0115] Frequency beam shifting method, optical cone transformation method, back projection method, or virtual wave phasor field method.

[0116] The above embodiments provide some commonly used free-space light field inversion techniques. In other embodiments, other free-space light field inversion methods can also be used to invert the target light field image. The specific free-space light field inversion method used can be selected according to the target reflection type and the detection method (i.e., the method of acquiring the light signal).

[0117] Furthermore, the free-space optical field inversion method is a frequency beamshifting method; step 106, "inverting the target optical field image using the free-space inversion method," includes:

[0118] A coordinate transformation is performed, making the z-axis plane where the light signal exits the cloud a known z=0 plane, and the frequency-domain filtered scattered field I(r,t) is transformed to Ψ(x,y,z=0,t); where x corresponds to r x y corresponds to r y The value remains unchanged, z corresponds to r z The value changes (the z-axis plane where the light signal exits the cloud corresponds to z=0), but t remains unchanged;

[0119] Performing a Fourier transform on the coordinate-transformed scattered field Ψ(x,y,z=0,t) yields the corresponding frequency domain expression Φ(k x ,k y ,f); f represents the time frequency, k x k y and k z These represent the spatial frequencies corresponding to the x, y, and z directions, respectively. Since z = 0, the transformed frequency domain representation does not include k. z ;

[0120] Using dispersion relations and Get containing k x k y and k z Frequency domain representation of the scattered field:

[0121]

[0122] For containing k x k y and k z The frequency domain expression of the scattering field Φ(k) x ,k y ,k z Perform an inverse Fourier transform to obtain the target scattering field Ψ(x,y,z,t=0).

[0123] This invention also provides an image enhancement method for inverting and imaging targets obscured by clouds and fog, comprising:

[0124] Step 200: Obtain the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range during which the pulse light is collected after being reflected by the target and penetrating the clouds and fog.

[0125] Step 202: Construct an image enhancement filtering function, and convolve the reflected three-dimensional light field with the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is:

[0126]

[0127] Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time;

[0128] Step 204: Determine the characteristics of the clouds and fog, and obtain the boundless cloud and fog transfer function; the characteristics of the clouds and fog include the reduced scattering coefficient of the clouds and fog, the speed of light in the clouds and fog, and the maximum thickness of the clouds and fog; the boundless cloud and fog transfer function φ inf The expression for (t,r) is:

[0129]

[0130]

[0131] Where t represents the transmission time of the optical signal, and r = (r x ,r y ,r z ) represents the point in the cloud from which the light signal is emitted, r x r y and r z Let x, y, and z represent the coordinates of the exiting cloud point, respectively, where z is the direction of light diffusion in the cloud, r0 = (0,0,0) represents the incident point of the light signal in the cloud, c represents the speed of light in the cloud, and μ s ' represents the reduced scattering coefficient of clouds and fog, z effect This represents the equivalent propagation distance, where light travels through an infinitely large cloud. effect The diffusion behavior of light is similar to the propagation of light in clouds of finite size. z The diffusion behavior is equivalent to z effect Not exceeding the maximum thickness d of the cloud / fog;

[0132] Step 206, the equivalent propagation distance z effectAs a variable, the enhanced filtered light field is frequency-domain filtered based on the aforementioned unbounded cloud and fog transport function, and then the target light field is inverted using the free-space light field inversion method to determine the equivalent propagation distance z. effect The correspondence between the inverted target light field imaging results and the actual results;

[0133] Step 208, based on the equivalent propagation distance z effect The correspondence between the inverted target light field imaging results and the final imaging results is determined by parametric scanning or optimization solution.

[0134] Existing technologies for simulating light transmission through clouds and fog typically require strictly defining the boundaries and constraining the shape of the clouds and fog, and necessitate calculating numerous parameters. However, in practical applications, it is often difficult to define the boundaries of clouds and fog, and the shapes of clouds and fog are irregular. Without clearly defined boundaries, existing technologies often struggle to accurately invert the target image.

[0135] The above embodiments provide a method for inverting and imaging targets obscured by clouds and fog. This method is based on a boundless cloud and fog transfer function, where the equivalent propagation distance z in the boundless cloud and fog transfer function is... effect This is a length parameter, whose value is generally smaller than the maximum thickness d of the cloud; by changing z effect The magnitude of the z-value can produce different imaging results; for different z-values... effect By filtering the corresponding imaging results and selecting the best image, the target light field imaging can be realized without acquiring cloud and fog boundary information, thus obtaining better imaging results.

[0136] Optionally, step 200 further includes:

[0137] Illuminate targets obscured by clouds and fog with a monochromatic pulsed laser;

[0138] On the transmitting side, a single-photon detector is used to acquire the time-domain optical signal waveform of each two-dimensional spatial point by scanning. The time-domain optical signal waveform includes the peaks caused by target reflection, but does not include the peaks caused by cloud and fog reflection.

[0139] Based on the spatial positional relationship of the two-dimensional scanning points, the time-domain optical signal waveforms corresponding to each scanning point are combined to obtain the reflected three-dimensional light field.

[0140] Optionally, the image enhancement filtering function includes:

[0141] Determine the frequency ω of the sine function based on the spatial interval Δr between points in two-dimensional space. c represents the speed of light in clouds and fog;

[0142] Based on the spatial interval Δr of the two-dimensional spatial points, determine the width a of the rectangular window function, where a is 10 to 15 times Δr;

[0143] The center position t0 of the rectangular window is determined based on the number of discrete sampling points of the image enhancement filtering function;

[0144] The image enhancement filtering function is obtained.

[0145] like Figure 5 and Figure 6 As shown, this embodiment of the invention provides an image enhancement device for retrieving and imaging targets obscured by clouds and fog. The device embodiment can be implemented through software, hardware, or a combination of both. From a hardware perspective, such as... Figure 5 The diagram shown is a hardware architecture diagram of an electronic device for image enhancement of cloud-occluded targets inversion imaging provided in an embodiment of the present invention. Besides... Figure 5 In addition to the processor, memory, network interface, and non-volatile memory shown, the electronic device in the embodiment may also include other hardware, such as a forwarding chip responsible for processing packets. Taking software implementation as an example, such as... Figure 6 As shown, as a logical device, it is formed by the CPU of its electronic device reading the corresponding computer program from the non-volatile memory into memory and running it. This embodiment provides an image enhancement device for retrieving and imaging targets obscured by clouds and fog, comprising:

[0146] The acquisition module 601 is used to acquire the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range in which the pulse light is collected after being reflected by the target and penetrating the clouds and fog.

[0147] Enhancement module 602 is used to construct an image enhancement filtering function and perform a convolution operation between the reflected three-dimensional light field and the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is:

[0148]

[0149] Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time;

[0150] The filtering module 603 is used to perform frequency domain filtering on the enhanced filtered light field based on the cloud and fog transfer function;

[0151] Inversion module 604 is used to invert the target light field image based on the frequency domain filtered light field using the free space inversion method.

[0152] In this embodiment of the invention, the acquisition module 601 can be used to execute step 100 in the above method embodiment, the enhancement module 602 can be used to execute step 102 in the above method embodiment, the filtering module 603 can be used to execute step 104 in the above method embodiment, and the inversion module 604 can be used to execute step 106 in the above method embodiment.

[0153] Optionally, the acquisition module 601 is used to measure the time-domain signal distributed in two-dimensional space, i.e., the reflected three-dimensional light field, or to read the reflected three-dimensional light field.

[0154] The acquisition module 601 may include a detector to measure the reflected three-dimensional light field. Existing reflected three-dimensional light field data may be stored on an optical disc, floppy disk, or computer hard drive. The acquisition module 601 may include a data reading module to read the reflected three-dimensional light field data and convert it into an executable format.

[0155] Optionally, the acquisition module 601 acquires the reflected three-dimensional light field of the target obscured by clouds and fog, including:

[0156] Illuminate targets obscured by clouds and fog with a monochromatic pulsed laser;

[0157] On the transmitting side, a single-photon detector is used to acquire the time-domain optical signal waveform of each two-dimensional spatial point by scanning. The time-domain optical signal waveform includes the peaks caused by target reflection, but does not include the peaks caused by cloud and fog reflection.

[0158] Based on the spatial positional relationship of the two-dimensional scanning points, the time-domain optical signal waveforms corresponding to each scanning point are combined to obtain the reflected three-dimensional light field.

[0159] Optionally, the enhancement module 602 constructs an image enhancement filtering function including:

[0160] Determine the frequency ω of the sine function based on the spatial interval Δr between points in two-dimensional space. c represents the speed of light in clouds and fog;

[0161] Based on the spatial interval Δr of the two-dimensional spatial points, determine the width a of the rectangular window function, where a is 10 to 15 times Δr;

[0162] The center position t0 of the rectangular window is determined based on the number of discrete sampling points of the image enhancement filtering function;

[0163] The image enhancement filtering function is obtained.

[0164] Optionally, the inversion module 604 is also used to output the final imaging result, for example, to output the imaging result to a data window and an image window, and to store the result in a specified storage medium.

[0165] Optionally, the device may further include a result display module 605 for displaying the final imaging result in a graphical manner. The result display module 605 may employ a screen with text and graphics display capabilities to directly display the calculated imaging result.

[0166] It is understood that the structures illustrated in the embodiments of the present invention do not constitute a specific limitation on an image-enhanced cloud-obscured target inversion imaging device. In other embodiments of the present invention, an image-enhanced cloud-obscured target inversion imaging device may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0167] The information interaction and execution process between the modules in the above-mentioned device are based on the same concept as the method embodiment of the present invention, and the specific details can be found in the description of the method embodiment of the present invention, and will not be repeated here.

[0168] This invention also provides an electronic device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a cloud-obscured target inversion imaging method according to any embodiment of this invention.

[0169] This invention also provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program causes the processor to perform a cloud-obscured target inversion imaging method according to any embodiment of this invention.

[0170] Specifically, a system or apparatus equipped with a storage medium may be provided, on which software program code implementing the functions of any of the embodiments described above is stored, and the computer (or CPU or MPU) of the system or apparatus may read and execute the program code stored in the storage medium.

[0171] In this case, the program code read from the storage medium can itself implement the function of any of the above embodiments, and therefore the program code and the storage medium storing the program code constitute part of the present invention.

[0172] Storage media embodiments for providing program code include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, program code can be downloaded from a server computer via a communication network.

[0173] Furthermore, it should be clear that not only can the program code read by the computer be executed, but also the operating system or other components operating on the computer can be instructed based on the program code to perform some or all of the actual operations, thereby realizing the function of any of the embodiments described above.

[0174] Furthermore, it is understood that the program code read from the storage medium is written to the memory set in the expansion board inserted into the computer or to the memory set in the expansion module connected to the computer. Then, based on the instructions of the program code, the CPU or other components installed on the expansion board or expansion module execute some and all of the actual operations, thereby realizing the function of any of the above embodiments.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for image enhancement of cloud-obscured targets inversion imaging, characterized in that, The method includes: Acquire the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range during which the pulse light is collected after being reflected by the target and penetrating the clouds and fog; An image enhancement filtering function is constructed, and the reflected three-dimensional light field is convolved with the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is: Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time; Based on the cloud and fog transfer function, frequency domain filtering is performed on the enhanced filtered light field; Based on the frequency-domain filtered light field, the target light field is inverted and imaged using the free-space inversion method.

2. The cloud-obscured target inversion imaging method according to claim 1, characterized in that, The acquisition of the reflected three-dimensional light field of the target obscured by clouds and fog includes: Illuminate targets obscured by clouds and fog with a monochromatic pulsed laser; On the transmitting side, a single-photon detector is used to acquire the time-domain optical signal waveform of each two-dimensional spatial point by scanning. The time-domain optical signal waveform includes the peaks caused by target reflection, but does not include the peaks caused by cloud and fog reflection. Based on the spatial positional relationship of the two-dimensional scanning points, the time-domain optical signal waveforms corresponding to each scanning point are combined to obtain the reflected three-dimensional light field.

3. The cloud-obscured target inversion imaging method according to claim 1, characterized in that, The expression for the cloud and fog transmission function is: Where t represents the transmission time of the optical signal, and r = (r x ,r y ,r z ) represents the point in the cloud from which the light signal is emitted, r x r y and r z Let x, y, and z represent the coordinates of the exiting cloud point, respectively, where z is the direction of light diffusion in the cloud, r0 = (0,0,0) represents the incident point of the light signal in the cloud, c represents the speed of light in the cloud, and μ s ' represents the reduced scattering coefficient of clouds and fog, μ a The value represents the absorption coefficient of clouds and fog, and D represents the diffusion coefficient. z +n Indicates the virtual point source location, z -n This indicates the location of the virtual negative point source, and n represents the number of positive and negative point source pairs. z +n (1-2n)r z -4nz e -z0 z -n (1-2n)r z -(4n-2)z e +z0 n＝0,±1,±2,... z e z represents the extrapolated boundary distance, and z0 represents the average scattered optical path.

4. The cloud-obscured target inversion imaging method according to claim 2, characterized in that, The constructed image enhancement filtering function includes: Determine the frequency ω of the sine function based on the spatial interval Δr between points in two-dimensional space. c represents the speed of light in clouds and fog; Based on the spatial interval Δr of the two-dimensional spatial points, determine the width a of the rectangular window function, where a is 10 to 15 times Δr; The center position t0 of the rectangular window is determined based on the number of discrete sampling points of the image enhancement filtering function; The image enhancement filtering function is obtained.

5. The cloud-obscured target inversion imaging method according to claim 1, characterized in that, The frequency domain filtering of the enhanced filtered light field based on the cloud and fog transfer function includes: Based on the cloud and fog transfer function, the enhanced light field is frequency-domain filtered by blind deconvolution filtering, minimum mean square error filtering, geometric mean filtering, or least squares filtering.

6. The cloud-obscured target inversion imaging method according to claim 1, characterized in that, The free-space light field inversion method includes: Frequency beam shifting method, optical cone transformation method, back projection method, or virtual wave phasor field method.

7. A method for image enhancement of cloud-obscured targets inversion imaging, characterized in that, include: Acquire the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range during which the pulse light is collected after being reflected by the target and penetrating the clouds and fog; An image enhancement filtering function is constructed, and the reflected three-dimensional light field is convolved with the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is: Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time; The characteristics of clouds and fog are determined, and a boundless cloud and fog transfer function is obtained. These characteristics include the reduced scattering coefficient of the clouds and fog, the speed of light within the clouds and fog, and the maximum thickness of the clouds and fog. The boundless cloud and fog transfer function φ... inf The expression for (t,r) is: Where t represents the transmission time of the optical signal, and r = (r x ,r y ,r z ) represents the point in the cloud from which the light signal is emitted, r x r y and r z Let x, y, and z represent the coordinates of the exiting cloud point, respectively, where z is the direction of light diffusion in the cloud, r0 = (0,0,0) represents the incident point of the light signal in the cloud, c represents the speed of light in the cloud, and μ s ' represents the reduced scattering coefficient of clouds and fog, z effect This represents the equivalent propagation distance, where light travels through an infinitely large cloud. effect The diffusion behavior of light is similar to the propagation of light in clouds of finite size. z Equivalent diffusion behavior, z effect Not exceeding the maximum thickness d of the cloud / fog; The equivalent propagation distance z effect As a variable, the enhanced filtered light field is frequency-domain filtered based on the aforementioned unbounded cloud and fog transport function, and then the target light field is inverted using the free-space light field inversion method to determine the equivalent propagation distance z. effect The correspondence between the inverted target light field imaging results and the actual results; Based on the equivalent propagation distance z effect The correspondence between the inverted target light field imaging results and the final imaging results is determined by parametric scanning or optimization solution.

8. An image enhancement device for retrieving cloud-obscured targets, characterized in that, include: The acquisition module is used to acquire the reflected three-dimensional light field of the target obscured by clouds and fog; the reflected three-dimensional light field includes the light signal in the time domain corresponding to the two-dimensional space, and the time domain interval of the reflected three-dimensional light field includes the time range in which the pulse light penetrates the clouds and fog after being reflected by the target and is collected; The enhancement module is used to construct an image enhancement filtering function and convolve the reflected three-dimensional light field with the image enhancement filtering function to obtain the enhanced and filtered light field; the expression of the image enhancement filtering function is: Where ω is the frequency of the sine function, a is the width of the rectangular window function, t0 is the center position of the rectangular window, and t is time; The filtering module is used to perform frequency domain filtering on the enhanced filtered light field based on the cloud and fog transfer function; The inversion module is used to invert the target light field image based on the frequency domain filtered light field using the free space inversion method.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1-7.

10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed in the computer, it causes the computer to perform the method of any one of claims 1-7.

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